The present invention relates generally to cutting tools. In particular, the present invention relates to improved snips having a toggle link mechanism.
Various kinds of cutting tools have been designed which provide a leveraged mechanical advantage to a user during a cutting cycle. This mechanical advantage allows a user to cut hardened materials such as sheet metal by hand. In the tools of the prior art, however, the various mechanical linkages provide that a substantial amount of the mechanical advantage is lost toward the tips of the blades of the cutting tools as the blades converge during the cutting operation. This loss of mechanical advantage requires the user to apply a greater amount of force to complete a cut throughout the full length of the cutting stroke. The cutting operation is thus less efficient and more demanding on the user.
The prior art has further shortcomings. In particular, the cutting handle may not be elevated over the material being cut during the cutting operation, thereby further hindering the user. While it is common to provide scissor handles that are attached to the cutting blades in an offset fashion, such an arrangement makes the scissors awkward to use. Furthermore, the offset location of the handles from the blades causes the user to lose additional mechanical advantage, as the hand may not be efficiently positioned to deliver force relative to the tool.
It is a general object of the invention to provide a new and useful cutting tool for cutting, among other materials, sheet metal by hand which provides a substantial mechanical advantage for the user throughout the entire cutting operation. Another object that the present invention provides is a new and useful method of cutting sheet metal, and other materials, by using the cutting tool described herein.
One aspect of the present invention integrates a toggle link mechanism into an improved cutting tool. This toggle mechanism provides a mechanical advantage to the user throughout the entire cutting operation to facilitate cutting. This configuration also simplifies manufacture and improves the durability of the tool.
In yet another aspect of the invention, an elevated handle is also provided so that during the cutting operation, the user""s hand is raised from the cutting surface and free of the material being cut. When the cutting blade of the upper jaw section is substantially aligned with the horizontal plane and the cutting tool is in the closed position, the upper and lower handles are elevated from the upper jaw section.
In yet another aspect of the present invention, curved blades are provided which curve away from the material being cut during the cutting process. The curved blades further assist the user in maximizing cutting efficiency throughout the cutting cycle.
One embodiment of the claimed invention includes an upper handle having an upper jaw section, a gripping section suitable for being grasped and an intermediary section connecting the upper jaw section with the gripping section. The upper jaw section defines a blade portion and the upper jaw section is forward of the gripping section. The cutting tool further comprises a lower handle having a gripping section wherein the lower handle is pivotally attached to the upper handle at a handle pivot point. The lower handle may be pivoted toward the gripping section of the upper handle from an open position to a closed position. The lower handle also has a first link pivot point which is forward of the handle pivot point. The cutting tool further comprises a lower jaw pivotally attached to the upper jaw section of the upper handle at a jaw pivot point. The lower jaw also has a second link pivot point rearward of the jaw pivot point. The lower jaw also has a blade portion. The cutting tool further comprises a link pivotally attached to the lower handle at the first link pivot point. The link is pivotally attached to the lower jaw at the second link pivot point such that pulling the lower handle toward the gripping section of the upper handle moves the link. The link then causes the blade portion of the lower jaw to pivot toward the blade portion of the upper handle. The handle pivot point, the first link pivot point and the second link pivot point form a substantially straight line when the lower handle is in the closed position.
In accordance with another aspect of the invention, a second embodiment of the cutting tool is provided wherein the tool comprises an upper handle for holding the tool and a jaw pivotally connected with the handle and including a jaw link rigidly attached to the jaw. A means is also provided for inputting force connected with the upper handle and including a handle link rigidly attached to the handle. The utility tool further comprises a toggle action force transfer mechanism defined by an intermediary link extending between the jaw link and the handle link. Force inputted to the input means moves the intermediary link away from the upper handle.
The innovation may also be embodied in a method wherein a user employs a cutting tool with toggle link mechanism. The mechanism comprises the steps of providing a cutting tool comprising an upper handle, a lower handle, a link and a lower jaw. The upper handle is pivotally connected with the lower handle at a handle pivot point. The link is connected with the lower handle at a first link pivot point and is connected with the lower jaw at a second link pivot point. The lower jaw is pivotally connected with the upper handle and the lower jaw and upper handle define two blades. The steps of the method also provide for sheet material. The sheet material is placed in between the blades of the cutting tool when the cutting tool is in the open position. Force is applied to the lower handle by rotating the lower handle around the handle pivot point. The link moves in a downward direction as the lower handle is rotated so that the first link pivot point, the second link pivot point and the handle pivot point approach a substantially straight line. The lower jaw pivots so that the lower blade moves toward the upper blade, cutting the sheet material.